Modern telephone systems allow multiple parties at different locations to hold a conference. However, telephone conferences do not provide all of the conveniences of a face-to-face conference, where participants all meet at a common table in a meeting room.
For example, in a meeting room, participants can view an object of interest, such as a drawing or a product. Such viewing is not possible in a telephone conference.
The invention concerns systems for collaborative video conferencing, using the telephone system. The invention generates a common visual image which is distributed to several computers. The users of the computers can make annotations on the common image. When they do, the invention replicates the annotations on the displays of all computers.
The common visual image can contain different types of images, such as text, graphics, and video.